MEANDRINA 



213 



MEGATHERIUM 



Meandrina, (rae-an-dn'na). [Meandrine, the 

 French name.] = Brain-coral : a family of 

 corals, with furrows, formed by long rows 

 of mouths. 



Mean sun, v. Sun. 



Measles, (me'zlz). [G. Mascr, speck.] An 

 eruptive fever-like disease. 



Measurement, (mez'ur-ment). [Mesure, the 

 French word.] M. of angles: by degrees, 

 each degree=^ of a right angle. M. of 

 area, v. M. of space. M. of force, v. 

 Momentum. M. of length, v. M. of space. 

 M. of ii(/7i<=Photometry. M. of space: of 

 length, by feet, miles, leagues, &c.; of 

 area, by square feet, acres, square miles, 

 &c. ; of volume, by cubic feet, &c. M. of 

 surface = M. of area. M. of time : by 

 seconds, minutes, hours, &c. 



Measures. Coal M.: the upper portion of 

 the carboniferous strata, in which are found 

 beds of coal; v. Primary strata. French M., 

 v. Metric svstem. 



Meat, (met). [Mate, the A.-S. word.] Ex- 

 tract of M. Concentrated juice of meat. 

 Lean of Af.=Muscle. Hog's M.=Roots of 

 Boerhavia decumbens. 



Meatus, (me-a'tus). [The Latin word.] An 

 opening: especially used for the opening of 

 the ear. 



Mecca, Balm of. Obtained from Balsamo- 

 dendron myrrha. 



Mechanical, ( me-kan'i-kal ). [ Mechanicus, 

 the Latin word.] M. equivalent of keat= 

 1390 foot-pounds per thermal unit. M. 

 theory of /tra:= Dynamical theory, q.v. M. 

 work of a man's &orfy=l,430,000 foot-pounds, 

 half being used internally in the work of 

 circulation, respiration, &c., and the other 

 half being available for external work. M. 

 poivers:l. The lever: a movable rod with 

 one point fixed. 2. The wheel and axle: 

 a modification of the lever, v. Wheel. 3. 

 The inclined plane; a gradual ascent. 4. 

 The Wedge: a double inclined plane. 5. 

 The screiu: an inclined plane winding round 

 an axis. 



Mechanics, (me-kan'iks). [MechaniJcos, the 

 Greek word.] The science of the laws of 

 forces, as shown by matter in masses. 



Meconates, (mek'5-nats). [Meconic, q.v.] 

 M;jCyHO7: compounds of meconic acid with 

 a base. 



Meconic acid, (me-kon'ik). [Gk. mel-on, 

 poppy. ]=C 7 H 4 O7.3HoO : a crystalline poi- 

 sonous substance found in opium. 



Meconine, (mek'o-nin). [Meconic q.v.] = 

 Cl()Hio04 : a crystalline substance found in 

 opium. 



Meconopsis, ( me-ko-nop'sis ). [Gk. mekon, 

 poppy; opsis, appearance.]=Welsh poppy: a 

 plant belonging to Papaveracea?. 



Medeola. A gourd-like plant. M. virginaca 

 = Indian cucumber. 



Median, (me'di-an). [L. medius, middle.] 

 M.fins; peculiar to fishes. M. nerve: in the 

 arm, serving the fingers. 



Medicago, (med-i-ka/go). [The Greek name.] 

 =Medick : an herb belonging to Legunii- 

 nacese. M. disci/on)us=lledge-hogg. 



Medical science, The knowledge of the action 

 of medicines upon the animal system. He- 

 teropathy= Allopathy: the use of medicines 

 likely to counteract the given disease. 

 Homoeopathy: the use of medicines, usually 

 in minute doses, likely to cause the given 

 disease in a state of health. 



Medlar, (medlar). [Medle, the A.-S. name.] 

 =Pyrus Germanica: a plant of the apple 

 kind. 



Medulla, (me-dul'la). [L. medulla, marrow.] 

 1. Spinal cord: the centre of the nervous 

 system in vertebrate animals. 2.=Marrow: 

 a delicate variety of connective tissue. M. 

 oblongata: the hindermost part of the brain, 

 in contact with the spinal cord, from which 

 most of the cerebral nerves originate. 



Medullary, ( me-dul'la-ri ). [Medulla, q.v.] 

 The middle portion of the kidney. M. rays: 

 vertical plates of cellular tissue, which 

 radiate from the pith of an exogenous plant 

 to the bark. 



Medusa, (me-du'sa). [Classical.] Head of M. 

 =Algol, q.v. 



Medusae, (nie-du'sg). [Medusa z the typical 

 genus.] = Jelly-fishes= 

 Discophorse : a sub- 

 division of Hydrozoa; 

 gelatinous animals in 

 which the heart and 

 stomach are identical. 

 v. Acalephfe. Craspe- 

 dote M. = Gymnoph- 

 thalmata= Naked - eyed 

 M.: mostly small, and 

 phosphorescent. M. 

 with covered eyes: have Medusse. 



a membrane over the supposed eyes. M. 

 with naked eyes; have no such membrane. 



Medusoid, (me-du'soid). [Medusa, q.v. Gk. 

 eidos, form.] Medusa-like. Steganophthal- 

 mate M.=M. with covered eyes, now in- 

 cluded in Lucernaridae. 



Meerschaum, (mer'shawm). [Gk. meer, sea; 

 schaum, foam.] A soft, white, clayey mine- 

 ral, chiefly hydrated silicate of magnesium: 

 \ised for tobacco pipes, and, when fresh, also 

 as a kind of soap. 



Megaceros, (me-gas'e-ros). [Gk. megas, large; 

 keras, horn.] M. Ilibernicus=Irish elk: a 

 large stag, known only by fossil remains. 



Megaderma, (meg-a-der'ma). [Gk. megas, 

 large; derma, skin.] M. i7/ra=Lyre bat. 



Megalodon, (me-gal'o-don). [Gk. megas, large; 

 odous, tooth.] A molluscous animal, known 

 only by shells found in Devonian rocks. 



Megalosaurus, (meg-a-16-saw'rus), Gk. megas, 

 great; sauros, lizard.] A large carnivorous 

 lizard, moving chiefly on its hind limbs, 

 analogous in structure to the ostrich, known 

 only by fossil remains in Lias, Oolite, and 

 Wealden rocks. 



Megaptera, (me-gap'ter-a). [Gk. megas, great; 

 pteryx, fin. ]=Hump- backed whale : a cetacean 

 animal, named from its large fins. 



Megatherium, (meg-a-the'ri-um). [Gk. megas, 

 great; therion, beast.] An extinct animal 

 of large size, resembling the sloth in some 

 characters, belonging to Edentata: known 



